1. Field of the Invention
The present invention is related to an optical touch display system, and more particularly, to an optical touch display system for multiple touch points.
2. Description of the Prior Art
Modern touch display technologies are already widely applied in electronic products of all kinds, e.g. Automated Teller Machine (ATM), handheld electronic devices and display devices. Generally, touch display technologies can be found in three types: resistive, capacitative and optical, wherein resistive and capacitative touch displays position an object via detecting variations in electric fields on surfaces of the touch displays when the object comes in contact with a sensing device. On the other hand, an optical touch display positions an object by detecting interruptions in light paths or light variations caused by the object moving on the surface of the touch display.
Since touch devices utilizing optical touch display technologies do not require special manufacturing processes or components, and also manufacturing costs are little affected by dimensions, optical touch technology is a more cost-effective solution than resistive and capacitative touch displays for larger-scale applications. To achieve a light-weight structure, optical touch display technologies often dispose image sensors at corners of touch screens and utilize triangulation to determine coordinates of a touch object from different angles. However, for two or more touch objects, measurement accuracy is reduced due to shadowing and obstruction of light paths, resulting in less accurate or incorrect coordinates (ghost coordinates), causing inconvenience for various applications.